The aim of this proposal is to evaluate the carcinogenic potential of Herpes Virus 11 in the uterus of mice. The investigators have had considerable experience with coaltar hydrocarbon carcinogenesis of the cervix in mice. Pilot studies in c3H mice utilizing a weekly vaginal insertion of a cotton pledget containing a formalin inactivated Herpes Virus 11 resulted in cyto-pathological evidence of pre-invasive lesions similar to those seen in the human cervix. In over 35 percent the cytological and pathological changes progressed to frank invasive cancer, which was lethal to the host. This program of studies is aimed to explore the cytological and pathological characteristics of these lesions, the reversible characteristics of the precancerous lesions, the carcinogen potential of Herpes Simplex Virus 11 virion inactivated by other methods, possible similar activity of Herpes Simplex Virus 1 and other related virus in the same and different strains of mice. The immunological aspects of the problem will be investigated as to antigen antibody titres of non-responding and responding mice as well as the possibility of tumor immunity.